The purpose of this work is to develop a tool to search for a gradient profile with ternary or binary
mixtures in liquid chromatography, that can provide well-resolved chromatograms in the shortest time
for multianalyte analysis. This approach is based exclusively on experimental data and does not require
a retention time model of the compounds to be separated. The methodology has been applied for the
quantification of four primary aromatic amines (PAAs) using HPLC with fluorescence detector (FLD). Aniline (ANL), 2,4-diaminotoluene (TDA), 4,4
-methylenedianiline (MDA) and 2-aminobiphenyl (ABP) have
been selected since their importance in food contact materials (FCM).
In order to achieve that, partial least squares (PLS) models have been fitted to relate CMP (control
method parameters) and CQA (critical quality attributes). Specifically, PLS models have been fitted using
30 experiments for each one of the four CQA (resolution between peaks and total elution time), considering 33 predictor variables (the composition of the methanol and acetonitrile in the mobile phase and the
time of each one of the 11 isocratic segments of the gradient). These models have been used to predict
new candidate gradients, and then, some of those predictions (the ones with resolutions above 1.5, in absolute value, and final time lower than 20 min) have been experimentally validated. Detection capability
of the method has been evaluated obtaining 1.8, 189.4, 28.8 and 3.0 μg L−1 for ANL, TDA, MDA and ABP,
respectively.
Finally, the application of chemometric tools like PARAFAC2 allowed the accurate quantification of
ANL, TDA, MDA and ABP in paper napkins in the presence of other interfering substances coextracted
in the sample preparation process. ANL has been detected in the three napkins analysed in quantities
between 33.5 and 619.3 μg L−1, while TDA is present in only two napkins in quantities between 725.9
and 1908 μg L−1. In every case, the amount of PAAs found, exceeded the migration limits established in
European regulations.
